Stop Improper Federal Bonuses Act This bill prohibits a federal agency from awarding a bonus to any employee for five years after the end of a fiscal year in which the agency makes an adverse finding relating to the employee. An adverse finding is a determination that an employee's conduct violated (1) a policy of the agency for which the employee may be removed or suspended for at least 14 days, or (2) a law for which the employee may be imprisoned for more than one year. The bill requires an agency to issue an order directing an employee to repay a bonus awarded in any year in which an adverse finding is made, and the agency must allow such employee to repay such bonus using a repayment plan. As a condition of receiving a bonus awarded after this bill's enactment, an employee must certify that he or she will repay the bonus in accordance with such an order.